A conventional double-side polishing apparatus for polishing both side faces of a work, e.g., wafer, comprises: a lower polishing plate having an upper polishing face, on which a polishing pad is adhered; an upper polishing plate being located above the lower polishing plate and capable of moving upward and downward, the upper polishing plate having a lower polishing face, on which a polishing pad is adhered; a carrier being provided between the lower polishing plate and the upper polishing plate, the carrier having a through-hole for holding the work; a plate driving unit for rotating the lower polishing plate and the upper polishing plate about their axes; a carrier driving unit for rotating the carrier; a slurry supply hole being formed in at least one of the polishing plates; and a slurry supply pipe being connected with the slurry supply hole, the slurry supply pipe supplying slurry, which is sent from a slurry supply source, to the polishing pads via the slurry supply hole. The lower polishing plate, the upper polishing plate and the carrier are rotated, with supplying the slurry to the polishing pads, so as to polish the both side faces of the work sandwiched between the polishing plates.
In a part of the polishing pad covering the slurry supply hole of the polishing plate, a hole or crisscross cut lines are formed so as to introduce the slurry onto the polishing pads.
In case that the polishing pads are composed of unwoven cloth of a relatively soft material, e.g., polyurethane, even if the hole or the cut lines are formed in the polishing pads, there is little possibility of damaging the work.
These days, in case of polishing a hard work, e.g., SIC substrate, a laminated polishing pad, which is constituted by a fiber layer (including woven cloth) and a resin layer, are occasionally used. If the hole or the cut lines are formed in the laminated polishing pad, end faces of the fiber layer (e.g., outer circumferential face, inner face of the hole, cut faces of the cut lines) are ragged, so the polishing operation will be badly influenced. If the carrier is caught by the ragged polishing pads, the carrier will be crushed.
Thus, as disclosed in Japanese Laid-open Patent Publication No. 2009-226578, the end faces of the fiber layer is melt-treated so as to prevent the end faces from being ragged.
In case of melt-treating the end face of the fiber layer as disclosed in the Japanese laid-open patent publication, it is relatively easy to melt the outer circumferential face of the polishing pad. However, the hole or the cut lines are formed in a narrow area, so it is very difficult to melt the inner face of the hole or the cut faces of the cut lines. Especially, in case of melt-treating the cut lines, the cut lines will be closed.
Even if the end faces are melt-treated, a slurry supply hole exists in a polishing face of a polishing plate. Therefore, the end faces of the fiber layer, which have been melt-treated, exist in the surface of the polishing pads facing the work. The fiber layer is not ragged, but the end faces, which have been melt-treated and become hard, will damage the work.